Chemical pressure and electron doping effects in SrPd2Ge2 single crystals

Abstract

Sr(Pd1-xPtx)(2)Ge-2, SrPd2(Ge1-xSix)(2), and Sr(Pd1-xAgx)(2)Ge-2 single crystals were synthesized using a self-flux method to examine the effects of chemical pressure and electron doping on the superconductivity of SrPd2Ge2 superconductors. The highest enhanced superconducting phase transition temperature (T-c) was 3.26 K, which was observed in Sr(Pd1-xPtx)(2)Ge-2 at x = 0.0618. In contrast, the T-c of SrPd2(Ge1-xSix)(2) remained nearly constant as the amount of dopant increased, and electron doping in Sr(Pd1-xAgx)(2)Ge-2 suppressed the superconductivity. In addition, for x <= 0.0657, the superconducting upper critical field (H-c2) increased linearly with an increase in the value of x in Sr(Pd1-xPtx)(2)Ge-2, while H-c2 remained nearly constant in SrPd2(Ge1-xSix)(2). The results of the present study were compared with those of pnictide compounds with a ThCr2Si2-type structure. (C) 2012 American Institute of Physics. [doi:10.1063/1.3672089]